TABLE 3-III 



Texture Classification 



Texture Typical Porosity 



Rhombic — perfectly formed rhombs of nearly equal size, Vuggy, drusy crystals 



medium to coarse (usually pure dolomite) in vugs 



Sucrosic— sugary, similar to rhombic, but finer, lacking the Interstitial, 



perfection of crystal form; friable (usually calcitic tubular to cavernous 



dolomite) 



Microsucrosic — very finely sugary, often quite friable (dolo- Tubular to 



mitic limestone) cavernous 



Grainy — not visibly crystalline but with definite grains, often Pin point to tubular 



chalky in part (limestone or dolomitic limestone) or vermicular 



Subcrystalline — glassy or resinous mass (usually pure dolo- Sparse pin point, 



mite) tendency to fracture 



Slabby — very coarsely crystalline, uneven grain size (rarely Usually nonporous 

 dolomitic) 



Oolitic — spheroidal or smooth-surfaced grains with concentric Intergranular or 



internal structure isolated pin point 



Pseudo-Oolitic — rounded clastic grains simulating oolites Interstitial to 



isolated pin point 



ing should be stated in the sample descriptions, and, in cases of unusual color- 

 ing, shown on the strip log. Red and orange speckling and mottling often occur 

 above and adjacent to large structural uplifts. Red, green, and orange are often 

 associated with surface weathering, unconformities, and subsurface oxidation 

 through the action of circulating waters. 



Inclusions: The term "inclusion" is used herein with certain reservations. 

 Masses of noncarbonate material commonly called "inclusions" are in many 

 instances chemical replacements of the original rock. The distinction can usually 

 be made when the rock is viewed in thin or polished section, but not in the 

 rough chip. Anhydrite and gypsum commonly occur as small isolated masses 

 in the carbonate rock. These masses may be either replacements or inclusions 

 that are contemporaneous with the host rock. Cherts occur in a similar form, 

 and likely have a similar origin. Unless these masses can be identified as replace- 

 ments, it is better to describe them simply as inclusions — a non-specific term. 



Evaporite Rocks 



(Plotted in black-line symbols) 



Although some carbonates are evaporitic in origin, it is impracticable to so 

 treat them in well-sample work for the same reasons that clastic limestones are 

 not considered with the clastic group. This group is restricted to anhydrite, 

 gypsum, salt, and such other chlorides and sulphates as can be identified. 



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